[PATCH v6 00/14] Linux RISC-V trace framework and drivers

[Mayuresh Chitale]

This series adds 'gtrace' which is an architecture-neutral hardware trace
framework with RISC-V E-trace as its first backend. The 'gtrace' core framework
has the minimal shared plumbing (component registration, path create/destroy,
path start/stop, etc) and the RISC-V trace drivers are its first consumer.
It should be possible for the required ARM components to be adapted to the same
framework in a future.

This series also adds initial support for RISC-V trace compnent drivers.
The RISC-V trace v1.0 specification is already ratified and can be found at:
https://github.com/riscv-non-isa/e-trace-encap/releases/tag/v1.0.0-ratified
https://github.com/riscv-non-isa/tg-nexus-trace/releases/tag/1.0_Ratified

The RISC-V trace component drivers are designed to be agnostic to the
underlying trace protocol hence both RISC-V E-trace and RISC-V N-trace should
work fine. The discovery of trace protocl parameters are left to user-space
trace decoder.

In the future, there will be subsequent series adding:
1) Sysfs support
2) ACPI support
3) More trace drivers (such as funnel, ATB, etc)
4) Support for upcoming self-hosted trace specification
5) Arm component support under the gtrace framework
6) ... and more ...

These patches can also be found in the riscv_trace_support_v6 branch at:
https://github.com/mdchitale/linux.git

To test the patches, we need QEMU virt machine with RISC-V trace support
which can be found in rv-etrace branch at:
https://gitlab.com/danielhb/qemu.git

To capture gtrace data using perf on QEMU virt machine do the following:
1) Launch QEMU virt machine
   $ qemu-system-riscv64 -nographic -M virt -smp 2 -bios fw_dynamic.bin \
     -kernel Image -append "root=/dev/vda rw console=ttyS0 earlycon=sbi" \
     -drive file=rootfs.img,id=disk1,if=none,format=raw \
     -device virtio-blk-device,drive=disk1
2) Run perf record to capture gtrace data
   $ perf record --all-cpus -e gtrace/event=0x1/ <command>
3) The step2 would create a perf.data file which has the gtrace data.
   Now run perf report -D and look for PERF_RECORD_AUXTRACE event
   section(s) which point(s) to the actual gtrace data offset.

Changes since v5:
 - Moved the DT connection parsing into the gtrace core as gtrace-of.c.
 - Added start_count and a lock to the core's private component data
   to serialize start/stop/copyto_auxbuf operations. Dropped
   perf_buf_lock.
 - Added handling of partially enabled path by disabling all enabled
   components
 - Added cycle detection when walking the trace component graph
 - Added trace source ID configuration in the encoder driver
 - Added trace format (E-Trace/N-Trace) selection via the platform driver
   compatible string. It is used by encoder and perf drivers to set it
   into hardware and perf data header respectively
 - Modified the ramsink buffer setup to read back the trRamStart and
   trRamLimit registers, and program the sync frequency, memory format
   and stop-on-wrap settings at start time
 - Improved error handling and added path owner in the perf driver
 - Fixed several issues reported by sashiko-bot but some of its findings
   are deferred to a later version.

Changes since v4:
 - Introduced a new architecture-neutral 'gtrace' (Generic Trace) framework
   and moved the RISC-V trace drivers on top of it instead of a RISC-V-only
   'rvtrace' core.
 - Added new PATCH3 "gtrace: Add RISC-V platform driver for the gtrace
   framework" to split out the RISC-V platform/DT code from the core
   framework patch.
 - Moved all rvtrace driver sources from drivers/hwtracing/rvtrace/ to
   drivers/hwtracing/gtrace/, with single Kconfig, Makefile using
 - Made the perf driver (previously rvtrace-perf.c) architecture-neutral
   and moved it into the gtrace framework as gtrace-perf.c; PMU name
   changed from "rvtrace" to "gtrace"
 - Added new PATCH8 "perf: Add gtrace AUX buffer trace format type" to
   define PERF_AUX_FLAG_GTRACE_FORMAT_ETRACE which is used in later patches.
 - copyto_auxbuf() and gtrace_path_copyto_auxbuf() now take an output
   parameter so the AUX data format can be reported by the sink
   driver by setting PERF_AUX_FLAG_GTRACE_FORMAT_ETRACE.
 - Renamed the generic side of the perf tools support from rvtrace* to
   gtrace*. perf.data ABI is unchanged.
 - Fixed gtrace ramsink start/stop to call gtrace_enable_component()/
   gtrace_disable_component() to remove duplication with code in
   gtrace-core.c
 - Updated the MAINTAINERS patch to refer to gtrace framework instead of
   rvtrace

Changes since v3:
 - Rebased on Linux-7.1-rc1
 - Use kzalloc_obj() in-place of kzalloc() in PATCH2, PATCH3 and PATCH9
 - Improved PATCH7 to save the previous WP value

Changes since v2:
 - Rebased on Linux-7.0-rc1
 - Addressed Rob's comments on DT bindings in PATCH1
 - Addressed ref-count related issues in rvtrace_of_parse_outconns()
   of PATCH2
 - Made RVtrace framework more generic by avoiding implicit access
   to component registers in PATCH2
 - More improvements in trRamStart/Limit/WP programming and other
   improvments in PATCH7
 - Removed RVTRACE_BUF_LEN from PATCH9
 - Removed redundant page_size from PATCH10
 - Renamed found_etm in PATCH10
 - Removed rvtrace_recording_init() declaration from header in PATCH11

Changes since v1:
 - Rebased on Linux-6.18-rc3
 - Addressed Rob's comments in dt-bindings added by PATCH1
 - Get reference of conn->dest_fwnode and add missing break in
   rvtrace_of_parse_outconns() of rvtrace-platform drivers added
   by PATCH2
 - Added new inline function rvtrace_comp_is_empty() in PATCH2
   and used it in rvtrace_encoder_stop() added by PATCH5
 - Fixed trRamWPLow usage in PATCH7
 - Determine RAM sink buffer size based on component implementation
   ID and reduce default RAM sink buffer size to 1MB
 - Add new PATCH8 to enable DMA_RESTRICTED_POOL in RISC-V defconfig
   so that implementations with RAM sink address restrictions can
   be handled.

Anup Patel (7):
  dt-bindings: Add RISC-V trace component bindings
  hwtracing: gtrace: Initial implementation of gtrace framework
  gtrace: Add RISC-V platform driver for the gtrace framework
  gtrace: Add functions to create/destroy a trace component path
  gtrace: Add function to copy into perf AUX buffer
  riscv: Enable DMA_RESTRICTED_POOL in defconfig
  MAINTAINERS: Add entry for RISC-V trace framework

Mayuresh Chitale (7):
  gtrace: Add functions to start/stop tracing on a component path
  gtrace: Add RISC-V Trace encoder driver
  perf: Add gtrace AUX buffer trace format type
  gtrace: Add RISC-V Trace ramsink driver
  gtrace: Add perf driver for tracing using perf tool
  perf tools: Add RISC-V trace PMU record capabilities
  perf tools: Initial support for gtrace decoder

 .../bindings/riscv/riscv,trace-component.yaml | 120 +++
 MAINTAINERS                                   |  11 +
 arch/riscv/configs/defconfig                  |   1 +
 drivers/Makefile                              |   1 +
 drivers/hwtracing/Kconfig                     |   2 +
 drivers/hwtracing/gtrace/Kconfig              |  59 ++
 drivers/hwtracing/gtrace/Makefile             |   9 +
 drivers/hwtracing/gtrace/gtrace-core.c        | 858 ++++++++++++++++++
 drivers/hwtracing/gtrace/gtrace-of.c          | 126 +++
 drivers/hwtracing/gtrace/gtrace-perf.c        | 390 ++++++++
 drivers/hwtracing/gtrace/rvtrace-encoder.c    | 236 +++++
 drivers/hwtracing/gtrace/rvtrace-platform.c   | 186 ++++
 drivers/hwtracing/gtrace/rvtrace-ramsink.c    | 357 ++++++++
 drivers/hwtracing/gtrace/rvtrace.h            | 121 +++
 include/linux/gtrace.h                        | 332 +++++++
 include/uapi/linux/perf_event.h               |   5 +
 tools/include/uapi/linux/perf_event.h         |   5 +
 tools/perf/arch/riscv/util/Build              |   1 +
 tools/perf/arch/riscv/util/auxtrace.c         | 221 +++++
 tools/perf/util/Build                         |   1 +
 tools/perf/util/auxtrace.c                    |   4 +
 tools/perf/util/auxtrace.h                    |   1 +
 tools/perf/util/gtrace-decoder.c              |  95 ++
 tools/perf/util/gtrace.h                      |  18 +
 24 files changed, 3160 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/riscv/riscv,trace-component.yaml
 create mode 100644 drivers/hwtracing/gtrace/Kconfig
 create mode 100644 drivers/hwtracing/gtrace/Makefile
 create mode 100644 drivers/hwtracing/gtrace/gtrace-core.c
 create mode 100644 drivers/hwtracing/gtrace/gtrace-of.c
 create mode 100644 drivers/hwtracing/gtrace/gtrace-perf.c
 create mode 100644 drivers/hwtracing/gtrace/rvtrace-encoder.c
 create mode 100644 drivers/hwtracing/gtrace/rvtrace-platform.c
 create mode 100644 drivers/hwtracing/gtrace/rvtrace-ramsink.c
 create mode 100644 drivers/hwtracing/gtrace/rvtrace.h
 create mode 100644 include/linux/gtrace.h
 create mode 100644 tools/perf/arch/riscv/util/auxtrace.c
 create mode 100644 tools/perf/util/gtrace-decoder.c
 create mode 100644 tools/perf/util/gtrace.h


base-commit: 551c722f40809618230001baccf219193e22fc5a
-- 
2.43.0